Increased harbour seal mortality in the Wadden Sea

+++Update from 21.11.2014+++

1578 severely sick or dead harbour seals were found at the west coast of Schleswig-Holstein to date, with the vast majority reported from the islands of Sylt, Helgoland, Amrum and Föhr. Only few more dead seals were found over the last couple of days and most of these animals seemed to be dead for a while. Therefore, the National Park Administration is expecting the disease to subside. Almost 90% of harbour seals in the area survived the influenza epidemic.

In Lower Saxony few more than 100 dead animals were found and the influenza H10N7 was confirmed. In the Netherlands first dead harbour seals were reported, while results of the laboratory analysis are pending.

+++Update from 08.11.2014+++

1400 dead harbour seals were found at the west coast of Schleswig-Holstein so far. However, there is no evidence that the level of mortality, caused by H10N7 influenza viruses, is increasing.

During last week rising numbers of dead harbour seals were reported from the island of Norderney in Lower Saxony. The analysis of dead animals, lead by the Lower Saxony State Office for Consumer Protection and Food Safety (LAVES), is expected to confirm influenza viruses as cause of the mortalities.

No observations of an unusual number of dead harbour seals were reported from the Netherlands to date.

+++Update from 28.10.2014+++

Statement of the Trilateral Seal Expert Group (TSEG) concerning the increased mortality of Harbour seals in Denmark and Schleswig-Holstein:

Arising in Kattegat in spring, the avian influenza H10N7 has spread to the Wadden Sea during September and October causing increased mortality among harbor seals in Denmark and Schleswig-Holstein. Although the epidemic causes the death of hundreds of seals, the TSEG does not regard it as a threat to the population based on the present mortality. The TSEG does not recommend rehabilitation of sick seals.

Generally, as other free-living animals seals can carry different diseases transmissible to humans and other animals, people are advised to keep away from living or dead seals to avoid infection. The same applies to dogs.

+++ Update from 24.10.2014 +++

The number of dead seals found at the west coast of Schleswig-Holstein increased to 500. The virus type responsible for the increased mortality in Denmark and Schleswig-Holstein was identified by the National Veterinary Institute of the Technical University of Denmark and by the University of Veterinary Medicine Hannover in Büsum as influenza serotype H10N7. Investigations are still progressing. The phocine distemper virus (pdv) has not been detected. No affected seals have been found at the coasts of Lower Saxony and the Netherlands to date.

+++ Update from 20.10.2014 +++

The number of dead seals found at the west coast of Schleswig-Holstein increased to 350. Meanwhile, the investigations by the University of Veterinary Medicine Hannover in Büsum and Hannover revealed that dissected animals died from pneumonia and suffered from lungworms and bacteria (streptococci). The majority of seals were also infected by an influenza strain found in seals in Denmark since July 2014. The phocine distemper virus (pdv) has not been detected.

+++ Original message from 16.10.2014 +++

Since the end of September, an increased number of dead or severely sick harbour seals has been reported from the Danish Wadden Sea coast and few days later also from the west coast of Schleswig-Holstein. To date about 180 dead animals were counted in Schleswig –Holstein, mainly at the shores of the islands of Helgoland, Sylt, Amrum and Föhr. The increased mortality has affected a significant number of animals older than one year, which is rather unusual.

The reason for this mortality remains unclear, while investigations are currently being carried by the University of Veterinary Medicine Hannover in Büsum. The investigations will clarify if influenza viruses, found in dead seals along Danish shores since July 2014, are involved. Detailed results are expected by the end of this week. Up to now, no evidence has been found that the mortality is caused by the phocine distemper virus (pdv), responsible for the massive seal epidemics in 1988 and 2002. The seal population of the west coast of Schleswig-Holstein consists of approx. 12,000 animals. At this stage, no predictions about possible impacts on the whole population of seals in the Wadden Sea area, which is estimated at about 40,000 animals, can be made.